Method of and means for supporting and insulating electric conductors



(No Model.) 3 Sheets-Sheet I.

H. W. LEONARD. METHOD OF AND MEANS FOR SUPPORTING AND INSULATING ELECTRIC GONDUGTORS.

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MHHIIIHIIII (No Model.) 3 SheetsSheet 2 H. W. LEONARD. METHOD OF AND MEANS FOR SUPPORTING AND INSULATING ELECTRIC GONDUGTORS.

No. 586,133. Patented July 13,1897.

(No Model.) 3 SheetsSheet 3 H. W. LEONARD. METHOD OF AND MEANS FOR SUPPORTING-AND INSULATING ELECTRIC GONDUGTORS.

No. 586,133. Patented July 18, 1897.

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UNITED STATES PATENT OFFICE,

HARRY lVARl) LEONARD, OF EAST ORANGE, NEYV JERSEY.

METHOD OF AND MEANS FOR SUPPORTlNG AND INSULATING ELECTRIC CONDUCTORS.

SPECIFICATION forming part of Letters Patent lite. 586,183, dated July 13, 1897.

Application filed February 18, 1897. Serial No. 623,237. (No model.)

To (LZZ whom, it may concern:

Be it known that I, HARRY WARD llsonann, a citizen of the United States, residing at East Orange, in the county of Essex and State of New Jersey, have invented a certain new and useful Improvement in Supporting and Insulating Electric Conductors, of which the following is a specification.

This invention relates to rheostats, electric heaters, or other apparatus in which a conductor is attached to a support or to other conductors and suitably insulated therefrom, and in which apparatus changes of temperature cause unequal expansion between the conductor and the support or between it and other conductors; and my invention relates particularly to apparatus in which the conductor is insulated from and attached to the support or other conductors by an adhesive mineral or vitreous material-such, for instance, as enamel.

lleretotorc in insulating and attaching a conductor to a support by materials of the character referred to it has been the practice to entirely embed the conductor in the insulatin g material or to partially embed the same practically throughout its entire length. It has been found in practice that when a current is sent through the conductor so attached a strain is developed in the attaching material which tends to rupture the attachment between the conductor and the attaching material or between the support and the attaching material, or both. \V hen the conductor is embedded in and entirely surrounded by the attaching material, and especially when the cross-section of the conductor is quite large, this tendency to rupture the attaching material is very pronounced, and more so where very large currents are sent through the conductor, even though the current be in use for only a few seconds.

Such large momentary currents are met with, for example, in the case of motors which have to be started, accelerated, or reversed rapidly and which have connected with them masses of considerable weightsuch, for ex ample, as elevators, traveling cranes, pumps, locomotives, printing presses, guns, etc. Many forms of alternating-currcnt motors require excessive starting-currents relative to their tull-load-runuing current, even though the torque required to accelerate the load be not very large. There are many similar cases in the operation of arc-lights, electric turnaces, and many other forms of apparatus in which a rheostat would be of service and in which exceptionally large currents are occasionally developed. In the construction of electric heaters and arinatures for dynamoelectric machines and motors it is similarly desirable to attach and support the conductor in a manner which will permit of operating the conductor at high currents, either normally or abnormally, without impairing the apparatus.

For commercial reasons it is important to have the conductor follow the surface of the support or other conductor to which it is at tached and to lie close to the surface, so as to occupy the least space and offer the best means of attachment and also the best means of disposing of the heat energy developed in the conductor. It is also important in case the conductor is subjected to momentary large or excessive currents or to a current for a length of time which will cause the conductor to become quite hot and limp, and hence lose its original form, (which form it would retain so long as it retains its rigidity and elasticity,) that the form of the conductor, its disposition relative to the support, the mode of attachment to the support, and the form of the support shall be such that even under the conditions of use referred to no serious result will occur due to the sagging or displacement of the conductor.

The object of my invention is to overcome the difliculties referred to, and in carrying my invention into effect I attach the conductor to its support or to other conductors at intervals, so that the conductor between its points of support is free to expand without causing any in jurieus strain at the points of attachment, whereby unequal expansion between the conductor and its support or other conductor may occur without detriment to the apparatus.

In applying my invention to rhecstats or heaters I employ a support which is preferably in the form of a grate or grid or latticelike, the surface of which. is covered with a layer of insulating material upon which the shaped conductor is placed and caused to ad here at intervals either through the agency I of the insulating material or otherwise. This form of support permits air to circulate freely around the conductor, and the heat energy developed in the conductor is mostly and rapidly dissipated by radiation and partly by conduction to the support at the points of attachment. Another advantage of the preferred form of support is that it is much cheaper than the solid supports heretofore employed in rheostats and heaters of the character described, there being about one-quarter the weight of material. There is less insulating material employed, and the cost of manufacture is in general very much reduced. Instead of the grate or grid like support I may employ a solid plate provided with ribs or projections which are covered with insulating material and upon which the conductor is placed and to which it is attached, the conductor being supported entirely by the ribs or projections, and hence free to expand between the points of attachment. Usually I employ a metal supportsuch, for instance, as cast-iron; but other supportssuch as percelain, tiling, or similar materialmay sometimes be advantageouslyemployed. For the insulating material I prefer to use mineral or vitreous material, like enamel, which may be applied to the support and the conductor caused to adhere to the support by any of the methods now well understood.

I prefer to employ a conductor in the form of a ribbon or tape, which may be very thin and quite wide, so as to offer the maximum heat-radiating surface for a certain cross-section, and I also prefer to employ such a conductor in reilexed form. In the manufacture of rheostats and heaters it is extremely desirable to secure in a certain space an exact number of ohms while using a certain eonductor, and when using a ribbon form of conductor attached to a plate or similar structure it is important to have the resistance of the conductor uniformly distributed over the space allotted to each step of the resistance. The reileXed form of ribbon gives wide flexibility in handling such cases, since by making the loops of the ribbon close together or spreading them more or less the total length of ribbon for a certain size to be disposed in a certain space can be varied within wide limits.

In the manufacture of rheostats I have found that when rheostats having a solid flat metal plate with a conductor attached thereto throughout its length by a mineral or vitreous material, like enamel, are operated under the conditions above referred to the insulating material is caused to separate from the sup port, particularly in the middle, the layer of insulation bulging outward and cracking and impairing the usefulness of the apparatus. I find that when the conductor is attached at intervals only the strains developed at the points of support are not continuousthat is to say, the strains do not extend along the length of the conductor, and the cracking and bulging of the insulating layer as a whole cannot take place. At most the insulation might crack or become otherwise impaired at one or more points where the conductor is attached, but the cause for such rupture would not necessarily extend to other points of attachment, and such slight ruptures would not impair the usefulness of the apparatus. As a further means of isolating possible ruptures I provide the ribs of the grate or grid like support with depressions, so as to form depressions in the insulating material on each side of the conductor at the point of attachment. The effect of this is to cause the insulating material to crack at the depressions should a strain at the point of attachment tend to bulge the insulating material outward, and hence any strains developed at the points of attachment are not communicated laterally to other points of attachment. This effect may be accomplished in other ways, as will be readily understood. I have also found that in a rheostat having a grid-like support constructed in accordance with my invention four times as much energy can be continuously dissipated as in a rheostat having a solid plate of the same general dimensions as the grid-like support.

By my invention a very cheap and efficient form of atmospheric heater may be produced. For use in cars or other vehicles, for instance, the grid with the heating-conductor may be placed in the floor of the vehicle and air caused to enter the vehicle through the grids, producing a circulation of hot air.

My invention is illustrated in the accompanying drawings, in which Figure l is a plan view of the top plate A of a rheostat provided with an automatic controlling device such, for instance, as described in my application Serial No.6l3,2i2- and contact-plates a, which extend through the plate. The plate A may be of slate or other suitable material.

Figs. 2 and 3 are front and side views, respectively, of a rheostat, showing three sup ports B, upon which conductors are mounted, and which plates, together with the top plate A, are bolted to a supporting-platform (1. Any number of plates 13 may be employed in the rheostat or heater, according to requirements. The circuit connections between the conductors and the contacts a are omitted to avoid confusion.

There are numerous advantages to be obtained by constructing a rheostat or heater in the manner illustrated in Figs. 2 and 3. It is very desirable in the manufacture of rheostats to be able to make a standard form which may be employed with meters or other forms of translating devices of varying capacitythat is, assuming, for instance, that one of the plates illustrated is provided with a conductor suitable for handling a five-horsepower motor, such plate may be made as a standard and employed in handling motors of five, ten, fifteen, and twenty horse power,&c., by building up the rheostat from a number of such plates-that is to say, for a ten-horsepower motor two such plates would be employed, for a fifteenhorse-powermotor three plates, and in all cases the corresponding successive steps or sections of each plate will be connected in multiple-arc relation, and each set of sections connected in multiple will be connected to its proper contact-plate a of the top plate A. The grate or grid like support is of further advantage in this connection in that when a number of plates are built up the airspaces are continuous and form flues, so to speak, affording the best ventilation, as the current of air can flow upward freely through the air-spaces and meeting only the thin edges of the ribbon conductor. Another important advantage of this form of rheostat is that it overcomes a difiiculty met with in the use of ribbon-like conductors. There is a limit to the width of a ribbon which may be used in practice. To illustrate, let it be supposed that in order to obtain a given radiating-surface and number of ohms in a ribbon conductor it would be necessary to use a ribbon .004: of an inch in thickness and ten inches wide. The employment of such a rib bon would be prohibitive for practical rea sons. To overcome the practical difficulty, the ribbon might be made only two inches wide and .020 of an inch in thickness, but with such a ribbon there would be a large reduction in the radiating-surface and the ribbon would not have the desired flexibility, .020 of an inch being too rigid for the purpose. To secure the desired resultand the advantages of the very wide and thin ribbon,ten supports, for instance, may be employed, each support having a conductor one inch in width and .004: of an inch in thickness, the corresponding successive steps or sections of each plate being connected in multiple. The compound rheostat so formed would give a compound ribbon represented by 10X1X. 004, which is the equivalent of a ribbon 10X.004, and thus the same advantages of the very wide and thin ribbon are obtained, with the further advantage of having several independent ribbons independently attached, and the further advantage that should any one or more sections of any multiple be rendered useless from any cause the apparatus would not be rendered inoperative as a whole, since it is not a complete breakdown, as would be the case where but one plate was employed and any one section was ruptured. Aside from the advantages referred to this form of rheostat has the further advantage of being very compact and comparatively light, due to the grate or grid like support, and hence easy of transportation, and, furthermore, there would be no difficulty with the long length of thin ribbon employed, since the same is quite rigidly mounted, there being no long loose coils of wire, as heretofore employed in rheostats of considerable capacity.

Fig. 4: is a plan view of a supporting-plate B. As illustrated, this plate is in the form of a grate or grid having four studs 13, provided with holes for the bolts which secure the grid and top plate A to the platform. The plate has a number of ribs Z), the openings between the ribs being quite large, so that air may circulate freely around the conductor. The depressions in the ribs and the insulating material transmission of lateral strains are indicated at h. The supportingplates are also provided with flanges b to give the necessary strength and rigidity and to serve as a guard for the conductor. To further guard the conductor, I may provide a wire-gauze or other equivalent covering which will extend entirely around the plates 13, between top plate A and platform C. The

surface of the plate is provided with a layer of insulating material, preferably a mineral or vitreous material-such, for instance, as enan1eland the conductor D is placed thereon, as illustrated in Fig. 5, the points of attachment to the support being where the conductor rests on the ribs 7) and the attachment being obtained by the agency of the insulating material.

From Fig. 5 it will be seen that even though the conductor D be heated to avery high heat it will be free to expand between the points of attachment, and hence the points of at tachment will be free from injurious strain, and although the conductor may become quite limp, due to the high heat, no serious results will follow, because the conductor is well supported at many points and is free to sag by reason of the openings in the plate, and there is no danger of adjacent sections being forced into contact with each other.

Fig. 6 is an enlarged cross-section of a supporting-plate with a ribbon conductor attached thereto. In this View b indicates the layer of insulating material. The conductor is secured at intervals to binding-posts (Z, which pass through the plate and are insulated therefrom by sleeves d, of suitable insulating material. In attaching the conductor to the bindingposts I preferably employ copper clips 61 which are made from strips of metal bent over, as indicated in Fig. (5, with the ribbon conductor placed between the fold and secured by a screw (1 The other end of the clip is placed beneath a washer d, and when the nut of the binding post d is screwed down the whole is firmly clamped to the plate. The connections from the binding-post d to the contact-plates a of the plate A are made by wire connections, which may be soldered or otherwise secured, and all connections maybe made underneath the plate A.

Fig. 7shows a plate similar to that of Figs. 4t and 5, but illustrating a straight ribbon conductor.

Fig. 8 illustrates a solid plate E, provided with raised ribs 6, upon which the conductor D is placed and secured by insulating material 11 as shown in Fig. 9, which is an end view of the plate of Fig. 8. The conductor is secured to binding-posts by clips (1 in the manner illustrated in Fig. 6. The effect of the arrangement of Fig. 8 is practically the same as that of Figs. 5 and 7, and, if desired to increase the ventilation, the plate may be provided with openings, as illustrated by the dotted lines 6.

Fig. 10 shows an arrangement similar to that of Fig. 5, except that a coiled-wire conductorD is employed instead of a ribbon conductor, the points of attachment being at the ribs Z) to clips (Z and to the opposite end of the plate, as in Fig. 5.

Fig. 11 illustrates a grate or grid upon which the conductor D is placed along instead of across the ribs of the plate. In this form the plate is provided with a layer of insulating material, and at the points as the plate is provided with an additional layer of insulation, which serves to attach the conductor to the support.

Fig. 2 illustrates a plate in which the 0011- ductor is attached in a manner similar to that of Fig. 1lthat is, at intervals by layers a; of insulation. In this form the plate may be either solid or provided with holes, as indicated by dotted lines.

Fig. 13 illustrates a plate which may be either solid or open and in which the conductor D is held in position by staples or other suitable forms of fasteners g which are secured to the insulated plate by being caused to adhere thereto.

Fig. 1i illustrates a reflexed ribbon conductor D, which is placed sidewise to the plate and attached at intervals, as distinguished from being placed edgewise thereto and attached at intervals.

Fig. 15 illustrates a ribbon conductor coiled into a helix and attached at intervals to the support.

Fig. 16 indicates a round or ribbon-like conductor D, bent back and forth upon itself, the adjacent sections being spaced by slotted blocks .2, the conductor being held in the slots and secured to the blocks by a vitreous material, such as enamel, as indicated at z. This arrangement may be employed for spac ing and securing conductors or sections of conductors for use in any form of apparatus and may be utilized in this shape for attachment to any of the forms of supporting-plates illustrated in the other figures.

Fig. 17 is a cross-section of two plates with a very wide ribbon conductor D between them, the two edges of the conductor preferably being attached at intervals to the upper and lower plates B and 13 This form is suitable where conductors of considerable width are utilizedfor instance, an inch and a half to two inches in width.

Fig. 18 is a plan view, and Fig. 19 a crosssection, of a form of plate having longitudinal walls 10, between which a reflexcd ribbon conductor D is placed edgewise, the conductor resting on cross-ribs 'w, to which it is caused to adhere bya vitreous material. In this form the surfaces of the walls to will be covered with a layer of insulation, either vitreous, like enamel, or any other suitable material, and the reflexed ribbon will be in contact with such insulated walls throughout its length. Vith this arrangement a large proportion of the heat energy is dissipated by conduction to the support, and, if desired, the support in its base maybe provided with openings, so as to afford ventilation and hence assist dissipation by convection.

Fig. illustrates a grate or grid having grooved ribs N, in which a spirally-wound conductor D may be placed and secured at intervals either at each rib or alternate ribs.

By vitreous material I mean any mineral material which for the purposes of my invention has the characteristics of glassthat is, any mineral material which will insulate the conductor from the support while attaching it thereto and which will withstand without injurious alteration the conditions to which it will be subjected in the practice of my invention.

I am aware that it has heretofore been proposed by others to employ in rheostats a ribbon-like reflexed conductor placed edgewise to the support and attached thereto at several points, as shown, for instance, in the patent to Shaw, No. 528,89i, dated November 6, 189%; also, that round conductors have been attached at intervals to a support, as shown in the patent to Gold, No. 510,211, dated June 4, 1895.

hat I claim is 1. The combination of a support and a conductor attached thereto at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, substantially as and for the purpose set forth.

2. The combination of a support and a conductor attached thereto at intervals through the agency of a vitreous material, the 0011- ductor being free to expand without subjecting the vitreous material to injurious strains, substantially as and for the purpose set forth.

3. The combination of a support and a ribbon-like conductor attached thereto at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, substantially as and for the purpose set forth.

4. The combination of a support and a ribbon-like conductor attached edgewise thereto at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, substantially as and for the purpose set forth.

5. The combination of a support and a ribhon-like conductor attached thereto at intervals through the agency of a vitreous material, the conductor being free to expand without subjecting the vitreous material to injurious strains, substantiallyas and for the purpose set forth.

6. The combination of a grid, grate or lattice like support, and a conductor attached thereto at intervals through the agency of an adhesive material, the conductor being free to expand Without subjecting the adhesive material to injurious strains, substantially as and for the purpose set forth.

7. The combination of a grid, grate or lattice like support, and a conductor attached thereto at intervals through the agency of a vitreous material, the conductor being free to expand without subjecting the vitreous material to injurious strains, substantially as and for the purpose set forth.

8. The combination of a grid, grate or lattice like support, and a ribbon-like conductor attached thereto at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, substantially as and for the purpose set forth.

9. The combination of a support and a reflexed ribbon-like conductor attached thereto at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, substantially as and for the purpose set forth.

10. The combination of a support and a reflexed ribbon-like conductor attached thereto at intervals through the agency of a vitreous material, the conductor being free to expand without subjecting the vitreous material to injurious strains, substantially as and for the purpose set forth.

11. The combination of a support, a layer of adhesive insulating material adherent thereto, and a conductor attached to said in sulated support at intervals through the agency of an adhesive material, the conductor being free to expand Without subjecting the adhesive material to injurious strains, substantially as and for the purpose set forth.

12. The combination of a support, a layer of adhesive insulating material adherent thereto, and a ribbon-like conductor attached to said insulated support at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, substantially as and for the purpose set forth.

13. In a rheostat, the combination of a support, a conductor arranged in sections and attached to said support at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, a series of ccntact-plates to which the sections of the conductor are attached, and a contactarm for making contact with said plates to place the sections of the conductor successively in to or out of circuit, substantially as set forth.

14. In a rheostat, the combination of a support, a ribbon-like conductor arranged in sections and attached to said support at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, a series of contact-plates to which the sections of the conductor are attached, and a contact-arm for making contact with said plates to place the sections of the conductor successively into or out of circuit, substan tially as set forth.

15. In a rheostat, the combination of a grid, grate or lattice like support, a conductor arranged in sections and attached to said support at intervals through the agency of an adhesive material, the conductor being free to expand without subjecting the adhesive material to injurious strains, a series of contactp1ates to which the sections of the conductor are attached, and a contact-arm for making contact with said plates to place the sections of the conductor successively into or out of circuit, substantially as set forth.

16. In a rheostat, the combination of a su pport, a conductor arranged in sections and attached to said support at intervals through the agency of an adhesive insulating material, the conductor being free to expand without subjecting the adhesive material to injurious strains, a series of contact-plates to which the sections of the conductor are attached, and a contact-arm for making contact with said plates to place the sections of the conductor successively into or out of circuit, substantially as set forth.

17. In a rheostat or electric heater, the combination of two or more supports and a conductor adhesively attached to each support, the conductor attached to each plate being arranged in sections and the corresponding sections of each conductor being connected in multiple-arc relation, substantially as and for the purpose set forth.

18. In a rheostat or electric heater, the combination of two or more supports and a conductor attached to each plate at intervals through the agency of an adhesive material, the conductor attached to each plate being arranged in sections and the corresponding sections of each conductor being connected in multiple-arc relation, substantially as and for the purpose set forth.

19. In a rheostat or electric heater, the.

combination of two or more grid, grate or lattice like supports and a conductor adhesively attached to each support, the conductor attached to each plate being arranged in sections and the corresponding sections of each conductor being connected in multiple-arc relation, substantially as and for the purpose set forth.

20. In a rheostat or electric heater, the combination of two or more supports and a ribbon-like conductor adhesively attached to each support, the conductor attached to each plate being arranged in sections and the corresponding sections of each conductor being connected in multiple-arc relation, substantially as and for the purpose set forth.

21. In a rheostat or electric heater, the combination of two or more supports and a ribbon-like conductor attached to each plate at intervals through the agency of an adhesive material, the conductor attached to each plate being arranged in sections and the corresponding sections of each conductor being connected in multiple-arc relation, substantially as and for the purpose set forth.

22. In a rheostat or electric heater, the combination of two or more grid, grate or lattice like supports and a ribbon-like conductor adhesively attached to each support, the cond uctor attached to each plate being arranged in sections and the corresponding sections of each conductor being connected in multipleare relation, substantially as and for the p u rpose set forth.

33. I11 a rheostat, the combination of two or more supports of the character herein described, conductors attached thereto at intervals through the agency of an adhesive material, the conductors being free to expand without subjecting the adhesive material to injurious strains, means for securing thesupports together, and mechanism for controlling and operating the rheostat or electric heater, substantially as set forth.

24. In a rheostat, the combination of two or more supports of the character herein described, ribbon-like conductors attached to each support at intervals through the agency of an adhesive material, the said conductors being arranged in sections and the corresponding sections of each conductor being connected in multiplearc relation to each other, means for securing the supports together, and mechanism for controlling and operating the rheostat, substantially as set forth.

25. In a rheostat, the combination of a support, a conductor arranged in sections and attached thereto at intervals through the agency of an adhesive material, a second support provided with a series of contact-buttons to which the sections of the conductor are attached,and a contact-lever mounted upon said second support, substantially as set forth.

26. In a rheostat, the combination of two or more supports, a conductor attached to each support, said conductors being arranged in sections and attached at intervals by the agency of an adhesive material and the c0rresponding sections of each conductor being connected in multiple-arc relation to each other, a support carrying a series of contactplates with which the sections of the conductors are connected, and a contact-1evermounted upon said latter support, substantially as set forth.

27. In a rheostat, the combination of two or more supports, a conductor attached to each support, said conductors being arranged in sections and attached at intervals by the agency of an adhesive material and the corresponding sections of each conductor being connected in multiple-arc relation to each other, a support carrying a series of contactplates with which the sections of the conductors are connected, and mechanism for controlling and operating the rheostat mounted upon said latter support, substantiall as set forth.

28. The combination of a support provided with a series of perpendicular partitions, and a reflexed ribbon-like conductor placed edgewise upon said support between said partitions, substantially as set forth.

29. The combination of a metal support provided witha series of perpendicular partitions, a retlexed ribbon-like conductor placed edgewise upon said support between said partitions, and a layer of suitable insulating material separating the conductor from the support and partitions, substantially as set forth.

30. The combination of a metal support provided with a series of perpendicular partitions, a reflexed ribbon-like conductor placed edgewise upon said support between said partitions, and a layer of vitreous insulating material like enamel separating the conductor from the support and partitions, substantially as set forth.

31. The combination of a metal support provided with a series of perpendicular partitions, a reflexed ribbon-like conductor placed edgewise upon said support between said partitions, a layer of suitable insulating material between said conductor and the partitions, and layers of adhesive insulating ma terial at intervals between the inner edge of said conductor and the support and whereby the conductor is attached at intervals to the support, substantially as set forth.

This specification signed and witnessed this 9th day of February, 1897.

II. WARD LEONARD.

lVitnesses:

W. PELZnn, JNo. R. TAYLOR.

ICO

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